The present invention relates to collapsible structures and, more particularly, to such structures including pivotable strut pairs that include stops for limiting pivotable movement of the struts.
A variety of types of collapsible structures (also often referred to as folding frame systems) are known. My U.S. Pat. No. 7,712,261, and my U.S. Pat. No. 7,556,054, which are incorporated by reference, disclose folding frame systems which can be locked in place by what can be referred to as a “tension lock”. In this tension lock arrangement, the frame is locked in an open position by pivotably connected strut members that are foldable from a parallel folded condition in which the struts lie substantially against each other, through a parallel open condition in which the struts are disposed substantially end-to-end, to an open locked condition slightly beyond the latter parallel condition beyond which the struts are prevented from pivoting. In this open locked condition, when a tension member is connected between points on the two struts removed from the pivot points, the tension member will prevent the struts from passing back to the parallel open or parallel folded positions unless the tension member is released or the struts are somehow deformed.
My U.S. Pat. Nos. 5,230,196, 5,444,946, and 6,141,934, which are incorporated by reference, disclose embodiments of folding frame systems with what can be referred to as “manual locks”. In these systems, strut pairs are arranged in scissor fashion, and, when the scissors are unfolded to open the system from a closed condition, ends of the struts are connected by hub portions that are manually locked together.
To simplify the construction of and erection and break-down of folding frame systems, it is desirable to provide a folding frame system that does not require a tension lock or a manual lock.
A structural module according to an aspect of the present invention comprises a first strut pair comprising a first strut and a second strut pivotably connected to each other at a first strut pair pivotable connection point, a second strut pair comprising a third strut and a fourth strut pivotably connected to each other at a second strut pair pivotable connection point, a first hub, a first end of the first strut and a first end of the third strut being pivotably connected to the first hub, a second hub, a first end of the second strut and a first end of the fourth strut being pivotably connected to the second hub, and a stop comprising a first and a second stop strut pivotably connected to each other proximate first ends thereof to at least partially define an abutment end of the stop, the first stop strut being pivotably connected at a second end thereof to the first strut and the second stop strut being pivotably connected at a second end thereof to the third strut. The structural module is movable between a closed position in which longitudinal axes of struts of the first strut pair and the second strut pair are substantially parallel to one another and an open position in which the abutment end of the stop contacts the second hub.
A collapsible structure according to an aspect of the present invention comprises a plurality of strut pairs, each strut pair comprising a front strut and a rear strut pivotably connected to each other at a strut pair pivotable connection point, a plurality of hub pairs, each hub pair comprising an outer hub and an inner hub, at least one first hub pair of the plurality of hub pairs being connected to at least a first and a second strut pair of the plurality of strut pairs so that an outer hub of the at least one first hub pair is pivotably connected to front struts of the first and second strut pair and an inner hub of the at least one first hub pair is pivotably connected to rear struts of the first and second strut pair, and a stop associated with at the at least one first hub pair, the stop comprising a first and a second stop strut pivotably connected to each other proximate first ends thereof, the first and the second stop strut being pivotably connected at second ends thereof to one of the front strut and the rear strut of the first and second strut pair, respectively.
A structural module according to another aspect of the present invention comprises a first strut pair comprising a first strut and a second strut pivotably connected to each other at a first strut pair pivotable connection point, a second strut pair comprising a third strut and a fourth strut pivotably connected to each other at a second strut pair pivotable connection point, a first hub, a first end of the first strut and a first end of the third strut being pivotably connected to the first hub, a second hub, a first end of the second strut and a first end of the fourth strut being pivotably connected to the second hub, and a stop arrangement attached to at least one of the first hub, the first strut, and the third strut, the stop arrangement including an abutment end. The structural module is movable between a closed position in which longitudinal axes of struts of the first strut pair and the second strut pair are substantially parallel to one another and an open position in which the abutment end of the stop contacts the second hub.
A method of erecting a collapsible structure according to an aspect of the present invention is also provided. The method involves use of a collapsible structure comprising a plurality of strut pairs, each strut pair comprising a front strut and a rear strut pivotably connected to each other at a strut pair pivotable connection point, a plurality of hub pairs, each hub pair comprising an outer hub and an inner hub, at least one first hub pair of the plurality of hub pairs being connected to at least a first and a second strut pair of the plurality of strut pairs to form a series of strut pairs so that an outer hub of the at least one first hub pair is pivotably connected to front struts of the first and second strut pair and an inner hub of the at least one first hub pair is pivotably connected to rear struts of the first and second strut pair, and a stop associated with at the at least one first hub pair, the stop comprising a first and a second stop strut pivotably connected to each other proximate first ends thereof, the first and the second stop strut being pivotably connected at second ends thereof to one of the front strut and the rear strut of the first and second strut pair, respectively. The method comprises moving each strut pair from a collapsed position in which the front and rear strut of each strut pair are substantially parallel to each other and hubs of the first hub pair are at a greatest possible distance from each other to an open position in which the stop prevents hubs of the first hub pair from moving closer to each other and after each strut pair is in an open position, restraining relative movement of the strut pairs of the series of strut pairs without locking inner and outer hubs to each other.